await server.ready hangs if started with exec_mode="task" and unable to start on the given port

[clintonstimpson]

Using this code:

        task = self.server.start(host=host, port=port, exec_mode="task", thread=True)
        await self.server.ready

I'm getting this error printed to the console:

future: <Task finished name='Task-18' coro=<WebAppServer.start() done, defined at ...wslink\backends\aiohttp_init_.py:139> exception=PermissionError(13, "error while attempting to bind on address ('0.0.0.0', 9000): [winerror 10013] an attempt was made to access a socket in a way forbidden by its access permissions")>

and there is a hang on await server.ready

It appears in trame_server/core.py, there is an on_done() method added to the task and within that a try/except block which catches the exception with no propagation of the exception.

[jourdain]

Is it your OS (Centos?) preventing trame to start on port 9000?

[clintonstimpson]

I'm actually seeing this on Windows right now, but I have another process binding to port 9000. I was looking at hardening my code to handle failures, and this error is one that led to a hang.

[jourdain]

You should be able to attach the done_callback on the task and check for the exception.
The ready will always hang as the server will never be ready.

[clintonstimpson]

Ok, if that's the way to do it, it works. I was wondering if it would make sense for the exception to propagate to await server.ready
If not, feel free to close this. I have a working solution now.

[jourdain]

As the ready property is a future, we could set_exception on it. That is a good idea. But we'll have to see how we want to connect those.

I'll keep it open for now.